This history of sex endocrinology discusses the emergence of the new field out of the scientific innovations and social concerns of the late nineteenth and early twentieth centuries. The gynecological and sexological context of the early discoveries in Germany, and the physiological context of the hormone theory in England set the background for analysis of American achievements and innovations that culminated in the textbook, Sex and Internal Secretions (1932). I also consider current social and cultural needs and attitudes in discussing the process by which granting decisions were made by the American Committee for Research in Problems of Sex. Likewise, the reasons for the social uses and interpretation of this research introduce the general conclusion of the book, a discussion of the relationship between scientific and social factors in early twentieth century biomedical research on sex.